Many linear electronic ballasts for fluorescent lighting applications that are sold on the market today include a standard ballast control IC, ASIC or micro-controller. These control ICs perform a variety of functions ranging from power factor correction to lamp/ballast control and have helped meet the technical requirements of new lamp types while reducing component count and cost. In self-ballasted compact fluorescent lamps (CFLs), the self-oscillating bipolar transistor solution is popular due to lower cost, lower component count and smaller size than the equivalent IC+FET-based solution.
This approach is very simple in nature but has the following disadvantages:                Non self-starting (requires a diac and additional circuitry);        Requires additional free-wheeling diodes;        Operating frequency determined by bipolar transistor storage time and toroid saturation;        Unreliable, “always hot” positive-temperature-coefficient (PTC) thermistor used for preheat;        No smooth frequency ramping during ignition;        No protection against lamp non-strike or open filament conditions;        Capacitive-mode operation; and        Base drive limitations at higher powers.        
These disadvantages can lead to component and load tolerances and/or catastrophic failure of ballast output stage components, which can result in poor performance, poor quality, and/or field failures.